SOLUTION: Need help with set up please!! I know the answer is 83 through playing with numbers, but I need to show it algebraically. thanks in advance The tens digit of a two-digit number

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Question 724360: Need help with set up please!! I know the answer is 83 through playing with numbers, but I need to show it algebraically. thanks in advance
The tens digit of a two-digit number is 5 more than the units digit. If "the number" is divided by the sum of its digits, the partial quotient is 7 and the remainder is 6. Find "the number."

Found 3 solutions by KMST, ankor@dixie-net.com, josmiceli:
Answer by KMST(5398) About Me  (Show Source):
You can put this solution on YOUR website!
a = tens digit
b = units digit
so the value of the number is 10a%2Bb and
the sum of the digits is a%2Bb
The tens digit is 5 more than the units digit translates as
a=b%2B5

Now comes the hard part:
If "the number" is divided by the sum of its digits, the partial quotient is 7 and the remainder is 6 translates as
10a%2Bb=7%28a%2Bb%29%2B6 (dividend = divisor x quotient + remainder)

Another way to see that:
The number divided by a%2Bb is 7 plus the fraction that we get when we divide the remainder by a%2Bb
%2810a%2Bb%29%2F%28a%2Bb%29=7%2B6%2F%28a%2Bb%29
Multiplying times a%2Bb both sides of the equal sign we get 10a%2Bb=7%28a%2Bb%29%2B6

Anyway,
10a%2Bb=7%28a%2Bb%29%2B6 --> 10a%2Bb=7a%2B7b%2B6 --> 3a%2Bb=7b%2B6 --> 3a=6b%2B6 --> 3a%2F3=%286b%2B6%29%2F3 --> a=2b%2B2
Now we have a system of linear equations:
system%28a=b%2B5%2Ca=2b%2B2%29 --> 2b%2B2=b%2B5 --> b%2B2=5 --> b=5-2 --> highlight%28b=3%29
system%28a=b%2B5%2Cb=3%29 --> a=3%2B5 --> highlight%28a=8%29

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
let a = the 10's digit
let b = the units
then
10a+b = "the number"
:
Write an equation for each statement
:
"The tens digit of a two-digit number is 5 more than the units digit."
a = b + 5
:
"If "the number" is divided by the sum of its digits, the partial quotient is 7 and the remainder is 6."
subtract the remainder (6) from the number to get an even 7
%28%2810a%2Bb-6%29%29%2F%28%28a%2Bb%29%29 = 7
multiply both sides by (a+b)
10a + b - 6 = 7(a+b)
10a + b - 6 = 7a + 7b
10a - 7a = 7b - b + 6
3a = 6b + 6
simplify, divide by 3
a = 2b + 2
Replace a with (b+5)
b + 5 = 2b + 2
5 - 2 = 2b - b
b = 3,
then
a = 3 + 5
a = 8
:
83 is the number
:
:
Check this, divide 83 by 11, 7 a remainder of 6



Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +u+ = the units digit
Let +t+ = the tens digit
given:
(1) +t+=+u+%2B+5+
(2) +%28+10t+%2B+u+%29+%2F+%28+t+%2B+u+%29+=+7+%2B+6%2F%28+t+%2B+u+%29+
------------------
Substitute (1) into (2)
(2)
(2) +%28+10u+%2B+50+%2B+u+%29+%2F+%28+2u+%2B+5+%29+=+7+%2B+6%2F%28+2u+%2B+5+%29+
Multiply both sides by +2u+%2B+5+
(2) +11u+%2B+50+=+7%2A%28+2u+%2B+5+%29+%2B+6+
(2) +11u+%2B+50+=+14u+%2B+35+%2B+6+
(2) +3u+=+9+
(2) +u+=+3+
and, since
(1) +t+=+u+%2B+5+
(1) +t+=+3+%2B+5+
(1) +t+=+8+
The number is 83
check answer:
(2) +%28+10t+%2B+u+%29+%2F+%28+t+%2B+u+%29+=+7+%2B+6%2F%28+t+%2B+u+%29+
(2) +%28+10%2A8+%2B+3+%29+%2F+%28+8+%2B+3+%29+=+7+%2B+6%2F%28+8+%2B+3+%29+
(2) +83%2F11+=+7+%2B+6%2F11+
(2) +83+=+77+%2B+6+
(2) +83+=+83+
OK